Well... a few thoughts...
1) in the age of "games as a service" is a game ever finished? The answer is no. So when precisely should someone offer a mod or not? The answer is simply that there is no right or wrong time, merely a matter of the work involved. Otherwise I'd have to ask exactly why an "unfinished game" is even for sale... I don't buy "unfinished" cars for example.
2) Do most gamers wait for the game to have sold its maximum number of DLC before playing? Are they aware they are playing an "unfinished product"? That would seem odd... why would companies sell DLC in portions if people only bought them when the game was "finished". What you might consider "finished" I would consider "Over". There's little joy for me in modding a product that has reached the end of its life-cycle, the audience has diminished and the hope of improvement for the platform is gone.
3) I don't think Horemvore was complaining about the amount of work involved with updating his mods due to frequent updates or the like, he was complaining about the quality and attitude of Stardock's work and their ability or lackthereof for fixing well documented problems. For example... the new expansion irreparably DISABLED all mods, even for those who didn't purchase Retribution... if Bethesda had done that with Skyrim... well they'd have a riot on their hands.
Now they fixed that within about 3-5 hours, which is quite good in my opinion, but I think Horemvore is continually disappointed with the glaring lack of quality assurance with StarDock and their design choices.
4) While Horemvore is often acerbic, and you could certainly argue his tone is overly emotional or an over-reaction (and he'd argue back I suppose), he's also been consistently helpful to the community and deserves to be treated squarely. If you want to argue with him... actually do that with a legitimate question.